Corrosion behavior of novel imitation-gold copper alloy with rare earth in 3.5% NaCl solution

A novel imitation-gold copper alloy with rare earth was designed and prepared. The corrosion behavior of the alloy immersed in 3.5% NaCl solution and its anti-tarnish property in the salt spray for different days has been studied. The designed alloy (CuZnAlNiMeRe) has more excellent anti-tarnish property and lower corrosion rate than those of currency coinage materials of H7211 alloy (used in China). A uniform and compact of corrosion film has been formed after the designed alloy immersed in 3.5% NaCl solution. The corrosion current densities Icorr of the alloy decreased while the polarization resistance Rp increased with time. The capacitance of the corrosion product film Cfilm of the alloy decreased while the charge transfer resistance Rct. The Warburg diffusion impedance WR and the resistance of the equivalent circuit R increased with time.

► The design alloy has better anti-tarnish property than that of H7211 alloy during salt-spray test.
► The corrosion rate of design alloy is much lower than that of H7211 alloy as immersed in NaCl solution.
► In the low frequency region, the capacitive behavior normally faded and diffusion process had a key role.
► In the medium frequency region, the Bode pattern showed a capacitive behavior.